CN113785545A

CN113785545A - Coefficient solution for low peak-to-average power ratio (PAPR) precoder

Info

Publication number: CN113785545A
Application number: CN201980096014.9A
Authority: CN
Inventors: P-A·拉波特
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2019-05-01
Filing date: 2019-05-01
Publication date: 2021-12-10
Also published as: US11956034B2; WO2020222034A1; US20220182112A1; EP3963848A1

Abstract

A network node is provided. The network node comprises processing circuitry configured to: determining at least one amplitude Convex Reduction (CRAM) projection matrix based at least in part on a signal subspace of scheduled wireless devices; and optionally causing transmission based at least in part on the at least one CRAM projection matrix.

Description

Coefficient solution for low peak-to-average power ratio (PAPR) precoder

Technical Field

Wireless communication, in particular, using a signal subspace to at least partially generate a projection matrix for wireless transmission.

Background

Fifth generation (5G, also known as new air interface (NR)) wireless systems introduce massive Multiple Input Multiple Output (MIMO) technology to further improve the spectral efficiency of mobile communication networks. The network node architecture may be radically affected because the number of antennas, along with the number of associated transmitter and receiver chains, may increase by approximately one order of magnitude. This paradigm shift can introduce complexity challenges to the design of network radio products, where size and power consumption can increase significantly if conventional design approaches are followed. These attributes may, in turn, be required by the network operator.

A low peak-to-average power ratio (PAPR) precoding algorithm provides a solution to this complexity problem by reducing the dynamic range of Orthogonal Frequency Division Multiplexing (OFDM) signals to a level that cannot be achieved using conventional Crest Factor Reduction (CFR) techniques. For example, a downlink waveform in a conventional cellular system may typically be associated with a first PAPR range, where a low PAPR precoder is capable of reducing the PAPR range below this first PAPR range. By taking advantage of the large number of degrees of freedom available in massive MIMO systems, low PAPR can be obtained. The low PAPR obtained using these techniques enables several radio optimizations, such as eliminating the traditional CFR, eliminating or reducing the complexity of the Digital Predistortion (DPD) algorithm, efficiently using smaller and less power demanding Power Amplifiers (PAs), using smaller cooling subsystems, potentially utilizing lower resolution data converters, and so forth.

Disclosure of Invention

Some embodiments advantageously provide a method, a wireless device and a network node for generating, at least in part, a projection matrix for wireless transmission using a signal subspace. According to one aspect of the disclosure, a network node comprises processing circuitry configured to: determining at least one amplitude Convex Reduction (CRAM) projection matrix based at least in part on a signal subspace of scheduled wireless devices; and optionally causing transmission based at least in part on the at least one CRAM projection matrix.

According to one or more embodiments of this aspect, the at least one CRAM projection matrix is based, at least in part, on a signal subspace of the interfering wireless devices. According to one or more embodiments of this aspect, the at least one CRAM projection matrix is based, at least in part, on the at least one precoding codebook entry. According to one or more embodiments of this aspect, the processing circuitry is further configured to: a signal subspace of a scheduled wireless device is determined based at least in part on tracking the at least one uplink channel.

According to one or more embodiments of this aspect, the processing circuitry is further configured to: determining a signal subspace of the scheduled wireless device based at least in part on tracking the precoded signal from the precoder. According to one or more embodiments of this aspect, the processing circuitry is further configured to: an indication of a signal subspace of a scheduled wireless device is received from a precoded signal from a precoder. According to one or more embodiments of this aspect, the processing circuitry is further configured to: an indication of a signal subspace of a scheduled wireless device is received from the scheduled wireless device.

According to one or more embodiments of this aspect, the signal subspace of the scheduled wireless device corresponds to an eigenvector associated with a channel response of the scheduled wireless device. In accordance with one or more embodiments of this aspect, the signal subspace of the scheduled wireless device is an M × K signal subspace, where M is the number of antennas of the network node and K is the number of multiple-input multiple-output, MIMO, layers. According to one or more embodiments of this aspect, the processing circuitry is further configured to: determining a multiple-input multiple-output, MIMO, precoder based at least in part on the at least one CRAM projection matrix, wherein the transmitting is based at least in part on the MIMO precoder.

According to another aspect of the disclosure, a method implemented in a network node is provided. At least one amplitude Convex Reduction (CRAM) projection matrix is determined based at least in part on a signal subspace of scheduled wireless devices. Causing transmission based at least in part on the at least one CRAM projection matrix. According to one or more embodiments of this aspect, the at least one CRAM projection matrix is based, at least in part, on a signal subspace of the interfering wireless devices. According to one or more embodiments of this aspect, the at least one CRAM projection matrix is based, at least in part, on the at least one precoding codebook entry.

According to one or more embodiments of this aspect, a signal subspace of a scheduled wireless device is determined based, at least in part, on tracking at least one uplink channel. According to one or more embodiments of this aspect, a signal subspace of the scheduled wireless device is determined based at least in part on tracking a precoded signal from a precoder. According to one or more embodiments of this aspect, an indication of a signal subspace of a scheduled wireless device is received from a precoded signal from a precoder.

According to one or more embodiments of this aspect, an indication of a signal subspace of a scheduled wireless device is received from the scheduled wireless device. According to one or more embodiments of this aspect, the signal subspace of the scheduled wireless device corresponds to an eigenvector associated with a channel response of the scheduled wireless device. In accordance with one or more embodiments of this aspect, the signal subspace of the scheduled wireless device is an M × K signal subspace, where M is the number of antennas of the network node and K is the number of multiple-input multiple-output, MIMO, layers. According to one or more embodiments of this aspect, a multiple-input multiple-output, MIMO, precoder is determined based at least in part on at least one CRAM projection matrix, wherein the transmission is based at least in part on the MIMO precoder.

According to another aspect of the disclosure, a wireless device includes processing circuitry configured to: providing auxiliary information associated with a signal subspace of a wireless device; and receiving a transmission based at least in part on the at least one CRAM projection matrix. The at least one CRAM projection matrix is based, at least in part, on a signal subspace of scheduled wireless devices that includes a signal subspace associated with the assistance information.

According to one or more embodiments of this aspect, the at least one CRAM projection matrix is based, at least in part, on a signal subspace of the interfering wireless devices. According to one or more embodiments of this aspect, the at least one CRAM projection matrix is based, at least in part, on the at least one precoding codebook entry. According to one or more embodiments of this aspect, the signal subspace of the scheduled wireless device corresponds to an eigenvector associated with a channel response of the scheduled wireless device.

In accordance with one or more embodiments of this aspect, the signal subspace of the scheduled wireless device is an M × K signal subspace, where M is the number of antennas of the network node and K is the number of multiple-input multiple-output, MIMO, layers. According to one or more embodiments of this aspect, the transmission is based at least in part on a multiple-input multiple-output, MIMO, precoder, which is based at least in part on at least one CRAM projection matrix.

In accordance with another aspect of the disclosure, a method implemented in a wireless device is provided. Auxiliary information associated with a signal subspace of a wireless device is provided. Receiving a transmission based at least in part on at least one CRAM projection matrix, wherein the at least one CRAM projection matrix is based at least in part on a signal subspace of scheduled wireless devices, including a signal subspace associated with assistance information.

In accordance with one or more embodiments of this aspect, the signal subspace of the scheduled wireless device is an M × K signal subspace, where M is the number of antennas of the network node and K is the number of multiple-input multiple-output, MIMO, layers. According to one or more embodiments of this aspect, the transmission is based at least in part on a multiple-input multiple-output, MIMO, precoder, wherein the MIMO precoder is based at least in part on at least one CRAM projection matrix.

According to another aspect of the disclosure, a network node comprises processing circuitry configured to: a plurality of amplitude Convex Reduction (CRAM) projection matrices are determined based at least in part on a signal subspace of scheduled wireless devices. The processing circuit is further configured to: determining a plurality of low peak-to-average power ratio (PAPR) precoders for a multiple-input multiple-output (MIMO) transmission based at least in part on the plurality of CRAM projection matrices; and causing transmission based at least in part on the low PAPR precoder.

In accordance with one or more embodiments of this aspect, the plurality of CRAM projection matrices are based, at least in part, on a signal subspace of the interfering wireless devices. According to one or more embodiments of this aspect, the signal subspace of the scheduled wireless device corresponds to an eigenvector associated with a channel response of the scheduled wireless device. In accordance with one or more embodiments of this aspect, the signal subspace of the scheduled wireless device is an M × K signal subspace, where M is the number of antennas of the network node and K is the number of MIMO layers.

Drawings

A more complete understanding of the present embodiments, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a block diagram of an example of CRAM processing;

FIG. 2 is a schematic diagram illustrating an exemplary network architecture of a communication system connected to a host computer via an intermediate network according to principles in this disclosure;

FIG. 3 is a block diagram of a host computer in communication with a wireless device via a network node through an at least partially wireless connection in accordance with some embodiments of the present disclosure;

FIG. 4 is a flow diagram illustrating an exemplary method implemented in a communication system including a host computer, a network node, and a wireless device for executing a client application at the wireless device in accordance with some embodiments of the present disclosure;

FIG. 5 is a flow chart illustrating an exemplary method implemented in a communication system including a host computer, a network node, and a wireless device for receiving user data at the wireless device in accordance with some embodiments of the present disclosure;

FIG. 6 is a flow chart illustrating an exemplary method implemented in a communication system including a host computer, a network node, and a wireless device for receiving user data from the wireless device at the host computer according to some embodiments of the present disclosure;

FIG. 7 is a flow chart illustrating an exemplary method implemented in a communication system including a host computer, a network node, and a wireless device for receiving user data at the host computer according to some embodiments of the present disclosure;

fig. 8 is a flow diagram of an example process in a network node in accordance with one or more embodiments of the present disclosure;

fig. 9 is a flow diagram of another exemplary process in a network node in accordance with one or more embodiments of the present disclosure;

FIG. 10 is a block diagram of one example of a CRAM cell in accordance with one or more embodiments of the present disclosure;

fig. 11 is a block diagram of another example of a CRAM cell in accordance with one or more embodiments of the present disclosure;

fig. 12 is a block diagram of yet another example of a CRAM cell in accordance with one or more embodiments of the present disclosure;

fig. 13 is a block diagram of yet another example of a CRAM cell in accordance with one or more embodiments of the present disclosure; and

fig. 14 is a flow diagram of an example process in a wireless device in accordance with one or more embodiments of the present disclosure.

Detailed Description

One example of a low PAPR precoding method is known as amplitude Convex Reduction (CRAM). This method has been described by Christoph student et al in the paper "Democratic Repressions", CORR abs/1401.3420, page 43 (hereinafter referred to as reference [1], the entire contents of which are incorporated herein by reference). While the CRAM method provides low computational cost, reference [1] only describes a single carrier system with zero-forcing (ZF) precoding.

In order to support many of the Practical constraints encountered in real-world systems, Mark Rollins et al extend the CRAM framework in PCT application IB2017/056155 entitled "Practical Low-PAPR Precoding System for Massive MIMO" (hereinafter reference [2], the entire contents of which are incorporated herein by reference) to support the following features:

global clipping per antenna;

port reduction;

reciprocity assisted interference aware transmission (RAIT) to reduce inter-cell interference;

multi-carrier and multi-band configurations;

incomplete channel knowledge.

For an OFDM system with N subcarriers and M antennas, shown in FIG. 1 from reference [2]]An example of the CRAM method of (1). CRAM processing engine 1 includes a receive multi (N)A frequency domain input signal

ZF precoder 2. Frequency domain input signal b_nAlso referred to herein as layer domain input vectors. For example, for a 20MHz LTE signal, N is 1200, and K is typically in the range of, for example, 2 to 8. The ZF precoder 2 is a linear precoder that inputs a signal b for each frequency domain_nPrecoding matrices P using respective ZFs_nPerforming digital beamforming separately to generate corresponding frequency domain precoded signals

One or more X-update functions 3-1 to 3-N input precoded signals X_ZF,nFrequency domain Z-update output signals from Z-update functions 13-1 to 13-M

And a projection matrix C input via a CRAM coefficient interface₁-C_NAnd generates a frequency domain X-update output signal

Outputting the frequency domain X-updating to X along the positive direction_n(N ═ 1.. times, N) is provided to the reordering function 4, which updates the vector X with N frequency domains X-each containing M samples_nRearranged into M vectors a each containing N frequency-domain samples_mA new set of (2). Rearranged vector a_m(M1.. said, M) is converted from the frequency domain to the time domain via a respective IFFT5-1 to 5-M to provide a time domain signal w for the M antenna branches, respectively_m(M ═ 1.., M). Then, for the M time domain signals w_mTime domain processing is performed. In this example, the time domain processing involves parallel-to-serial (P/S) conversion by P/S converters 6-1 through 6-M and a Cyclic Prefix (CP) prepended via CP-adding functions 7-1 through 7-M, respectively. Time domain clipping function 8-1 to 8-M pairs of M time domains for M antenna branchesThe transmit signal performs time domain slicing. In the reverse direction, the M clipped time domain transmit signals are fed back by respective CP removal discard CP functions 9-1 through 9-M and respective serial-to-parallel (S/P) converters 10-1 through 10-M to provide corresponding time domain clipped signals for the M antenna branches, respectively

M time-domain feedback signals. The M time-domain feedback signals are converted from the time domain to the frequency domain via respective FFTs 11-1 to 11-M. The rearrangement function 12 performs an inverse rearrangement of the frequency domain feedback signal to provide N frequency domain feedback signals y for the N subcarriers, respectively_n. N frequency domain feedback signals x_nAnd y_nAre provided to respective Z-update functions 13-1 to 13-N which perform a frequency domain Z-update procedure according to the prior art.

However, CRAM frames from the prior art are not without problems. Some projection matrices may be needed in this CRAM framework

(where n is the subcarrier index and M is the number of antennas) to help ensure that the spatial constraint is met in the X-update portion of the algorithm. These projection matrices are defined as:

wherein:

i is an M identity matrix;

·

is a channel matrix for subcarrier n, where K is the number of MIMO layers;

·

is a zero-forcing precoding matrix for subcarrier n and is represented as:

suppose a projection matrix C_nIs computed outside of the CRAM processing engine. For example, the computation of the projection matrix may be put together with the channel estimation function, and the CRAM processing engine may be physically located elsewhere within the network node 16, such as in another ASIC or FPGA chip, for example. Thus, as shown in fig. 1, an interface may be required to send the projection matrix to the CRAM engine. This interface is called the CRAM coefficient interface.

Assume that the radio system has the following specifications:

6 × 20MHz LTE carrier;

one CRAM projection matrix per Physical Resource Block (PRB);

100 PRBs per 20MHz LTE carrier;

64 antennas;

8 MIMO layers;

the real and imaginary parts of the CRAM projection coefficients are quantized with 12-bits;

LTE OFDM symbol rate of 15 KHz.

Each projection matrix is hermitian symmetric and has a size of M × M. Hermitian symmetry allows only about half of the matrix entries to be transferred across the CRAM coefficient interface. The number N of matrix entries (i.e., coefficients) to be conveyed for each PRB is defined as:

for a system with the above characteristics, the throughput requirements of the CRAM coefficient interface would be as follows:

for example, assuming that this interface would be implemented using serializer-deserializer (SERDES) lanes (each at 16Gbps), 29 data links would be required to meet this throughput requirement for communicating CRAM coefficients over the CRAM coefficient interface. This may have a negative impact on the complexity and power consumption of both the baseband unit and the radio unit.

The present disclosure advantageously helps address at least some of the above-mentioned problems by providing for exploiting signal subspace to address CRAM coefficient interface bandwidth challenges by reducing throughput requirements of the CRAM coefficient interface. In one or more embodiments, the coefficient interface is eliminated altogether.

Before describing in detail exemplary embodiments, it should be observed that the embodiments reside primarily in combinations of apparatus components and processing steps related to using a signal subspace to at least partially generate a projection matrix for wireless transmission. Accordingly, the components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Like numbers refer to like elements throughout.

As used herein, relational terms, such as "first" and "second," "top" and "bottom," and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

In the embodiments described herein, the connecting terms "in communication with … …," and the like, may be used to indicate that electrical or data communication may be accomplished, for example, through physical contact, induction, electromagnetic radiation, radio signaling, infrared signaling, or optical signaling. Those of ordinary skill in the art will appreciate that the various components are interoperable and that modifications and variations to implement electrical and data communications are possible.

In some embodiments described herein, the terms "coupled," "connected," and the like may be used herein to indicate a connection (although not necessarily a direct connection), and may include wired and/or wireless connections.

The term "network node" as used herein may be any kind of network node comprised in a radio network, which may further comprise any of the following: a Base Station (BS), a radio base station, a Base Transceiver Station (BTS), a Base Station Controller (BSC), a Radio Network Controller (RNC), a g-nodeb (gnb), an evolved node B (eNB or eNodeB), a node B, a multi-standard radio (MSR) radio node (such as MSR BS), a multi-cell/Multicast Coordination Entity (MCE), a relay node, a donor node controlling a relay, a radio Access Point (AP), a transmission point, a transmission node, a Remote Radio Unit (RRU) Remote Radio Head (RRH), a core network node (e.g., Mobile Management Entity (MME), a self-organizing network (SON) node, a coordination node, a positioning node, an MDT node, etc.), an external node (e.g., a third party node, a node external to the current network), a node in a Distributed Antenna System (DAS), a Spectrum Access System (SAS) node, Element Management Systems (EMS), etc. The network node may also comprise test equipment. The term "radio node" as used herein may also be used to denote a Wireless Device (WD) such as a Wireless Device (WD) or a radio network node.

In some embodiments, the non-limiting terms Wireless Device (WD) or User Equipment (UE) are used interchangeably. A WD herein may be any type of wireless device, such as a Wireless Device (WD), capable of communicating with a network node or another WD by radio signals. WD may also be a radio communication device, target device, device-to-device (D2D) WD, machine type WD or machine-to-machine communication (M2M) capable WD, low cost and/or low complexity WD, WD equipped sensors, tablet, mobile terminal, smartphone, Laptop Embedded Equipment (LEE), laptop installed equipment (LME), USB dongle, client equipment (CPE), internet of things (IoT) device, or narrowband IoT (NB-IoT) device, and the like.

Furthermore, in some embodiments, the generic term "radio network node" is used. It may be any kind of radio network node, which may comprise any of the following: a base station, a radio base station, a base transceiver station, a base station controller, a network controller, an RNC, an evolved node b (enb), a node B, gNB, a multi-cell/Multicast Coordination Entity (MCE), a relay node, an access point, a radio access point, a Remote Radio Unit (RRU) Remote Radio Head (RRH).

Note that while a set of terms from one particular wireless system, such as, for example, 3GPP LTE and/or new air interface (NR), may be used in this disclosure, this should not be taken as limiting the scope of the disclosure to only the above-described systems. Other wireless systems, including but not limited to Wideband Code Division Multiple Access (WCDMA), worldwide interoperability for microwave access (WiMax), Ultra Mobile Broadband (UMB), and global system for mobile communications (GSM), may also benefit from utilizing the concepts covered within this disclosure.

The indication may generally explicitly and/or implicitly indicate information that it represents and/or indicates. The implicit indication may be based on, for example, the resources and/or location used for the transmission. The explicit indication may be based on, for example, a parameterization having one or more parameters, and/or one or more indices, and/or one or more bit patterns representing information. It is specifically contemplated that the control signaling described herein implicitly indicates the type of control signaling based on the sequence of resources utilized.

Transmitting in the downlink may pertain to transmissions from a network or network node to a wireless device. Transmitting in the uplink may pertain to transmission from the wireless device to the network or network node. Transmitting in the sidelink may pertain to a (direct) transmission from one wireless device to another. Uplink, downlink, and sidelink (e.g., sidelink transmission and reception) may be considered as the direction of communication. In some variants, uplink and downlink may also be used to describe wireless communication between network nodes, e.g. for wireless backhaul and/or relay communication and/or (wireless) network communication, in particular communication terminating there between, e.g. between base stations or similar network nodes. Backhaul and/or relay communication and/or network communication may be considered to be implemented as a form of side link or uplink communication or the like.

It is further noted that the functions described herein as being performed by a wireless device or a network node may be distributed across multiple wireless devices and/or network nodes. In other words, it is envisaged that the functionality of the network node and the wireless device described herein is not limited to being performed by a single physical device, and may in fact be distributed among several physical devices.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Embodiments propose to use a signal subspace to at least partially generate and/or determine a projection matrix for wireless transmission.

Referring again to the drawings, wherein like reference numerals refer to like elements, there is shown in fig. 2a schematic diagram of a communication system 15, such as a 3 GPP-type cellular network that may support standards such as LTE and/or NR (5G), according to an embodiment, the communication system 15 including an access network 17, such as a radio access network, and a core network 14. The access network 17 includes a plurality of

network nodes

16a, 16b, 16c (collectively referred to as network nodes 16), such as NBs, enbs, gnbs or other types of radio access points, each defining a

corresponding coverage area

18a, 18b, 18c (collectively referred to as coverage areas 18). Each

network node

16a, 16b, 16c is connectable to the core network 14 by a wired or wireless connection 20. A first Wireless Device (WD)22a located in the coverage area 18a is configured to wirelessly connect to or be paged by a corresponding network node 16 c. A second WD22 b located in the coverage area 18b may be wirelessly connected to the corresponding network node 16 a. Although multiple WDs 22a, 22b (collectively referred to as wireless devices 22) are shown in this example, the disclosed embodiments are equally applicable where a single WD is in the coverage area or where a single WD is connected to a corresponding network node 16. Note that although only two WDs 22 and three network nodes 16 are shown for convenience, the communication system may contain many more WDs 22 and network nodes 16.

Further, it is contemplated that the WD22 may be in simultaneous communication with and/or configured to separately communicate with more than one network node 16 and more than one type of network node 16. For example, the WD22 may have dual connectivity with the same or different network nodes 16 that support LTE and network nodes 16 that support NR. As an example, the WD22 may communicate with an eNB for LTE/E-UTRAN and a gNB for NR/NG-RAN.

The communication system 15 itself may be connected to a host computer 24, and the host computer 24 may be implemented in hardware and/or software of a standalone server, a cloud-implemented server, a distributed server, or may be implemented as a processing resource in a server farm. Host computer 24 may be owned or controlled by or operated on behalf of the service provider. The

connections

26, 28 between the communication system 15 and the host computer 24 may extend directly from the core network 14 to the host computer 24, or may extend via an optional intermediate network 30. The intermediate network 30 may be one or a combination of more than one of a public network, a private network, or a hosted network. The intermediate network 30, if any, may be a backbone network or the internet. In some embodiments, the intermediate network 30 may include two or more sub-networks (not shown).

The communication system of fig. 2 as a whole enables connectivity between one of the connected WDs 22a, 22b and the host computer 24. The connectivity may be described as an over-the-top (OTT) connection. The host computer 24 and the connected WDs 22a, 22b are configured to communicate data and/or signalling via OTT connections using the access network 17, the core network 14, any intermediate networks 30 and possibly further infrastructure (not shown) as intermediaries. The OTT connection may be transparent in the sense that the participating communication devices through which the OTT connection passes are not aware of the routing of the uplink and downlink communications. For example, the network node 16 may not or need not be informed of past routing of inbound downlink communications with data originating from the host computer 24 to be forwarded (e.g., handed over) to the connected WD22 a. Similarly, the network node 16 need not be aware of future routing of outbound uplink communications originating from the WD22 a to the host computer 24.

The network node 16 is configured to include an amplitude convex reduction CRAM unit 32 configured to perform one or more functions described herein, such as with respect to using signal subspaces to at least partially generate projection matrices for wireless transmissions. An example implementation according to an embodiment of the WD22, the network node 16 and the host computer 24 discussed in the preceding paragraphs will now be described with reference to fig. 3. In the communication system 15, the host computer 24 comprises Hardware (HW)38, the hardware 38 comprising a communication interface 40 configured to establish and maintain a wired or wireless connection with interfaces of different communication devices of the communication system 15. Host computer 24 further includes processing circuitry 42 that may have storage and/or processing capabilities. Processing circuitry 42 may include a processor 44 and a memory 46. In particular, processing circuitry 42 may comprise, in addition to or in place of a processor such as a central processing unit and memory, integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (field programmable gate arrays) and/or ASICs (application specific integrated circuits) adapted to execute instructions. The processor 44 may be configured to access (e.g., write to and/or read from) the memory 46, and the memory 46 may include any kind of volatile and/or non-volatile memory, such as a cache and/or a cache memory and/or a RAM (random access memory) and/or a ROM (read only memory) and/or an optical memory and/or an EPROM (erasable programmable read only memory).

Processing circuitry 42 may be configured to control any of the methods and/or processes described herein and/or to cause such methods and/or processes to be performed, for example, by host computer 24. Processor 44 corresponds to one or more processors 44 for performing the functions of host computer 24 as described herein. Host computer 24 includes a memory 46, memory 46 being configured to store data, program software code, and/or other information described herein. In some embodiments, software 48 and/or host application 50 may include instructions that, when executed by processor 44 and/or processing circuitry 42, cause processor 44 and/or processing circuitry 42 to perform the processes described herein with respect to host computer 24. The instructions may be software associated with the host computer 24.

The software 48 may be executable by the processing circuitry 42. The software 48 includes a host application 50. The host application 50 may be operable to provide services to a remote user, such as a WD22 connected via an OTT connection 52 that terminates at the WD22 and the host computer 24. During the provision of services to remote users, the host application 50 may provide user data that is transferred using the OTT connection 52. The "user data" may be the data and information described herein to implement the functionality. In one embodiment, the host computer 24 may be configured to provide control and functionality to a service provider, and may be operated by or on behalf of the service provider. Processing circuitry 42 of host computer 24 may enable host computer 24 to observe, monitor, control, transmit to and/or receive from network node 16 and or wireless device 22. The processing circuitry 42 of the host computer 24 may include an information unit 54, the information unit 54 being configured to enable the service provider to perform one or more of the following operations on information relating to using the signal subspace to at least partially generate a projection matrix for wireless transmission: provide, forward, relay, determine, receive, transmit, communicate, store, etc.

The communication system 15 further includes a network node 16, the network node 16 being disposed in the communication system 15 and including hardware 58 that enables it to communicate with the host computer 24 and with the WD 22. The hardware 58 may include a communication interface 60 for establishing and maintaining wired or wireless connections with interfaces of different communication devices of the communication system 15, and a radio interface 62 for establishing and maintaining at least one wireless connection 64 with the WD22 located in the coverage area 18 served by the network node 16. Radio interface 62 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and/or one or more RF transceivers. The communication interface 60 may be configured to facilitate a connection 66 with the host computer 24. The connection 66 may be direct or it may pass through the core network 14 of the communication system 15 and/or through one or more intermediate networks 30 external to the communication system 15.

In the illustrated embodiment, the hardware 58 of the network node 16 further includes a processing circuit 68. The processing circuitry 68 may include a processor 70 and a memory 72. In particular, the processing circuitry 68 may comprise, in addition to or instead of a processor such as a central processing unit and a memory, an integrated circuit for processing and/or control, e.g. one or more processors and/or processor cores and/or an FPGA (field programmable gate array) and/or an ASIC (application specific integrated circuit) adapted to execute instructions. The processor 70 may be configured to access (e.g., write to and/or read from) the memory 72, and the memory 72 may include any kind of volatile and/or non-volatile memory, such as a cache and/or a buffer memory and/or a RAM (random access memory) and/or a ROM (read only memory) and/or an optical memory and/or an EPROM (erasable programmable read only memory).

Thus, the network node 16 further has software 74, either internally storing the software 74 in, for example, the memory 72, or storing the software 74 in an external memory (e.g., a database, storage array, network storage, etc.) accessible to the network node 16 via an external connection. The software 74 may be executable by the processing circuitry 68. Processing circuitry 68 may be configured to control any of the methods and/or processes described herein and/or to cause performance of such methods and/or processes, for example, by network node 16. Processor 70 corresponds to one or more processors 70 that are configured to perform the functions of network node 16 described herein. Memory 72 is configured to store data, program software code, and/or other information described herein. In some embodiments, software 74 may include instructions that, when executed by processor 70 and/or processing circuitry 68, cause processor 70 and/or processing circuitry 68 to perform the processes described herein with respect to network node 16. For example, the processing circuitry 68 of the network node 16 may include the CRAM unit 32 configured to perform one or more network node functions described herein, such as with respect to using signal subspaces to at least partially generate projection matrices for wireless transmissions.

The communication system 15 further comprises the already mentioned WD 22. The WD22 may have hardware 80, and the hardware 80 may include a radio interface 82, the radio interface 82 configured to establish and maintain the wireless connection 64 with the network nodes 16 serving the coverage area 18 in which the WD22 is currently located. Radio interface 82 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and/or one or more RF transceivers.

The hardware 80 of the WD22 further includes processing circuitry 84. The processing circuitry 84 may include a processor 86 and a memory 88. In particular, the processing circuitry 84 may comprise, in addition to or instead of a processor such as a central processing unit and memory, integrated circuitry for processing and/or control, e.g. one or more processors and/or processor cores and/or FPGAs (field programmable gate arrays) and/or ASICs (application specific integrated circuits) adapted to execute instructions. The processor 86 may be configured to access (e.g., write to and/or read from) the memory 88, and the memory 88 may include any kind of volatile and/or non-volatile memory, such as a cache and/or a cache memory and/or a RAM (random access memory) and/or a ROM (read only memory) and/or an optical memory and/or an EPROM (erasable programmable read only memory).

Thus, the WD22 may further include software 90, the software 90 being stored, for example, in the memory 88 at the WD22, or in an external memory (e.g., a database, storage array, network storage, etc.) accessible to the WD 22. The software 90 may be executable by the processing circuitry 84. The software 90 may include a client application 92. The client application 92, with the support of the host computer 24, may be operable to provide services to human or non-human users via the WD 22. In host computer 24, executing host application 50 may communicate with executing client application 92 via OTT connection 52 that terminates at WD22 and host computer 24. During the provision of services to the user, client application 92 may receive request data from host application 50 and provide user data in response to the request data. The OTT connection 52 may carry both request data and user data. Client application 92 may interact with a user to generate user data that it provides.

Processing circuitry 84 may be configured to control any of the methods and/or processes described herein and/or to cause performance of such methods and/or processes, for example, by WD 22. The processor 86 corresponds to one or more processors 86 for performing the functions of the WD22 described herein. WD22 includes a memory 88 configured to store data, program software code, and/or other information described herein. In some embodiments, software 90 and/or client application 92 may include instructions that, when executed by processor 86 and/or processing circuitry 84, cause processor 86 and/or processing circuitry 84 to perform the processes described herein with respect to WD 22. For example, the processing circuitry 84 of the wireless device 22 may include a channel estimation unit 34, the channel estimation unit 34 configured to perform one or more wireless device functions described herein, such as with respect to a projection matrix for wireless transmission.

In some embodiments, the internal workings of the network node 16, WD22, and host computer 24 may be as shown in fig. 3, and independently, the surrounding network topology may be that of fig. 2.

In fig. 3, OTT connection 52 has been abstractly drawn to illustrate communication between host computer 24 and wireless device 22 via network node 16 without explicitly mentioning any intermediary devices and the precise routing of messages via these devices. The network infrastructure may determine routing, which may configure the routing to be hidden from the WD22 or from the service provider operating the host computer 24, or both. When OTT connection 52 is active, the network infrastructure may further make a decision (e.g., based on load balancing considerations or reconfiguration of the network) by which it dynamically changes routing.

The wireless connection 64 between the WD22 and the network node 16 is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments use the OTT connection 52 to improve the performance of OTT services provided to the WD22, where the wireless connection 64 may form the last leg. More particularly, teachings of some of these embodiments may improve data rate, latency, and/or power consumption and thereby provide benefits such as reduced user latency, relaxed limits on file size, better responsiveness, extended battery life, and so forth.

In some embodiments, a measurement process may be provided in order to monitor the data rate, latency, and other factors improved by one or more embodiments. There may further be optional network functionality for reconfiguring the OTT connection 52 between the host computer 24 and the WD22 in response to changes in the measurements. The measurement process and/or network functionality for reconfiguring the OTT connection 52 may be implemented in the software 48 of the host computer 24 or in the software 90 of the WD22 or both. In embodiments, sensors (not shown) may be deployed in or in association with the communication devices through which OTT connection 52 passes; the sensor may participate in the measurement process by supplying the values of the monitored quantities exemplified above or by supplying the values of other physical quantities from which the

software

48, 90 may calculate or estimate the monitored quantities. The reconfiguration of OTT connection 52 may include message format, retransmission settings, preferred routing, etc.; the reconfiguration need not affect the network node 16 and it may be unknown or imperceptible to the network node 16. Some such processes and functionalities may be known and practiced in the art. In certain embodiments, the measurements may involve proprietary WD signaling that facilitates the measurement of throughput, propagation time, latency, and the like by the host computer 24. In some embodiments, the measurement may be implemented by: the

software

48, 90 causes messages, particularly null or 'dummy' messages, to be transmitted using the OTT connection 52 while it monitors propagation time, errors, etc.

Thus, in some embodiments, the host computer 24 includes processing circuitry 42 configured to provide user data and a communication interface 40 configured to forward the user data to the cellular network for transmission to the WD 22. In some embodiments, the cellular network also includes a network node 16 having a radio interface 62. In some embodiments, the network node 16 is configured and/or the processing circuitry 68 of the network node 16 is configured to perform the functions and/or methods described herein for preparing/initiating/maintaining/supporting/terminating transmissions to the WD22 and/or preparing/terminating/maintaining/supporting/terminating reception of transmissions from the WD 22.

In some embodiments, host computer 24 includes processing circuitry 42 and a communication interface 40, with communication interface 40 configured as a communication interface 40 configured to receive user data originating from transmissions from WD22 to network node 16. In some embodiments, WD22 is configured to, and/or includes radio interface 82 and/or processing circuitry 84 and is configured to perform the functions and/or methods described herein for preparing/initiating/maintaining/supporting/terminating transmissions to network node 16 and/or preparing/terminating/maintaining/supporting/terminating reception of transmissions from network node 16.

Although fig. 2 and 3 represent various "units" such as CRAM unit 32 and channel estimation unit 34 as being within respective processors, it is contemplated that these units may be implemented such that a portion of the units are stored in corresponding memories within the processing circuitry. In other words, these units may be implemented in hardware or in a combination of hardware and software within the processing circuitry.

Fig. 4 is a flow diagram illustrating an exemplary method implemented in a communication system, such as, for example, the communication systems of fig. 2 and 3, in accordance with one embodiment. The communication system may include host computer 24, network node 16, and WD22, which may be those described with reference to fig. 3. In a first step of the method, the host computer 24 provides user data (block S100). In an optional sub-step of the first step, host computer 24 provides user data by executing a host application, such as, for example, host application 50 (block S102). In a second step, the host computer 24 initiates a transmission to the WD22 carrying user data (block S104). In an optional third step, the network node 16 transmits to the WD22 user data carried in a transmission initiated by the host computer 24 in accordance with the teachings of embodiments described throughout this disclosure (block S106). In an optional fourth step, WD22 executes a client application, such as, for example, client application 92 associated with host application 50 executed by host computer 24 (block S108).

Fig. 5 is a flow diagram illustrating an exemplary method implemented in a communication system, such as, for example, the communication system of fig. 2, in accordance with one embodiment. The communication system may include host computer 24, network node 16, and WD22, which may be those described with reference to fig. 2 and 3. In a first step of the method, the host computer 24 provides user data (block S110). In an optional sub-step (not shown), host computer 24 provides user data by executing a host application, such as, for example, host application 50. In a second step, the host computer 24 initiates a transmission to the WD22 carrying user data (block S112). This transmission may be via the network node 16 in accordance with the teachings of the embodiments described throughout this disclosure. In an optional third step, the WD22 receives the user data carried in the transmission (block S114).

Fig. 6 is a flow diagram illustrating an exemplary method implemented in a communication system, such as, for example, the communication system of fig. 2, in accordance with one embodiment. The communication system may include host computer 24, network node 16, and WD22, which may be those described with reference to fig. 2 and 3. In an optional first step of the method, the WD22 receives input data provided by the host computer 24 (block S116). In an optional sub-step of the first step, WD22 executes a client application 92, which client application 92 provides user data in reaction to received input data provided by host computer 24 (block S118). Additionally or alternatively, in an optional second step, the WD22 provides user data (block S120). In an optional sub-step of the second step, WD provides the user data by executing a client application, such as, for example, client application 92 (block S122). The executed client application 92 may further consider user input received from the user during the provision of the user data. Regardless of the particular manner in which the user data is provided, WD22 may initiate transmission of the user data to host computer 24 in an optional third sub-step (block S124). In a fourth step of the method, the host computer 24 receives user data transmitted from the WD22 in accordance with the teachings of embodiments described throughout this disclosure (block S126).

Fig. 7 is a flow diagram illustrating an exemplary method implemented in a communication system, such as, for example, the communication system of fig. 2, in accordance with one embodiment. The communication system may include host computer 24, network node 16, and WD22, which may be those described with reference to fig. 2 and 3. In an optional first step of the method, the network node 16 receives user data from the WD22 according to the teachings of embodiments described throughout this disclosure (block S128). In an optional second step, the network node 16 initiates transmission of the received user data to the host computer 24 (block S130). In a third step, host computer 24 receives user data carried in a transmission initiated by network node 16 (block S132).

Fig. 8 is a flow diagram of an example process in the network node 16 in accordance with one or more embodiments of the present disclosure. One or more blocks and/or functions performed by network node 16 may be performed by one or more elements of network node 16, such as by CRAM unit 32, processor 70, radio interface 62, etc. in processing circuitry 68. As described herein, in one or more embodiments, the network node 16 (such as via one or more of the processing circuitry 68, the processor 70, the communication interface 60, and the radio interface 62) is configured to determine (block S134) at least one amplitude convex reduction CRAM projection matrix based at least in part on a signal subspace of the scheduled wireless devices 22. As described herein, in one or more embodiments, the wireless device (such as via one or more of the processing circuitry 84, the processor 86, and the radio interface 82) is configured to cause (block S136) transmission, optionally based at least in part on the at least one CRAM projection matrix.

In accordance with one or more embodiments, the at least one CRAM projection matrix is based at least in part on a signal subspace of the interfering wireless devices 22. In accordance with one or more embodiments, the at least one CRAM projection matrix is based, at least in part, on the at least one precoding codebook entry. In accordance with one or more embodiments, the processing circuitry 68 is further configured to determine a signal subspace of the scheduled wireless devices 22 based at least in part on tracking the at least one uplink channel.

In accordance with one or more embodiments, the processing circuitry 68 is further configured to determine a signal subspace of the scheduled wireless devices 22 based at least in part on tracking the precoded signal from precoder 2. In accordance with one or more embodiments, the processing circuitry 68 is further configured to receive an indication of the signal subspace of the scheduled wireless device 22 in the precoded signal from precoder 2. In accordance with one or more embodiments, the processing circuit 68 is further configured to receive an indication of a signal subspace of the scheduled wireless device 22 from the scheduled wireless device 22.

In accordance with one or more embodiments, the signal subspace of a scheduled wireless device 22 corresponds to the eigenvectors associated with the channel response of the scheduled wireless device 22. In accordance with one or more embodiments, the signal subspace of the scheduled wireless device 22 is an M × K signal subspace, where M is the number of antennas of the network node 16, and K is the number of multiple-input multiple-output, MIMO, layers. In accordance with one or more embodiments, the processing circuitry 68 is further configured to determine a multiple-input multiple-output MIMO precoder based at least in part on at least one CRAM projection matrix, the transmission being based at least in part on the MIMO precoder.

Fig. 9 is a flow diagram of another exemplary process in the network node 16 in accordance with one or more embodiments of the present disclosure. One or more blocks and/or functions performed by network node 16 may be performed by one or more elements of network node 16, such as by CRAM unit 32, processor 70, radio interface 62, etc. in processing circuitry 68. As described herein, in one or more embodiments, the network node 16 (such as via one or more of the processing circuitry 68, the processor 70, the communication interface 60, and the radio interface 62) is configured to determine (block S138) a plurality of amplitude convex reduction CRAM projection matrices based at least in part on a signal subspace of the scheduled wireless devices 22. In one or more embodiments, the network node 16 (such as via one or more of the processing circuitry 68, the processor 70, the communication interface 60, and the radio interface 62) is configured to determine (block S140) a plurality of low peak-to-average power ratio (PAPR) precoders for a multiple-input multiple-output, MIMO, transmission based at least in part on the plurality of CRAM projection matrices. In one or more embodiments, the network node 16 (such as via one or more of the processing circuitry 68, the processor 70, the communication interface 60, and the radio interface 62) is configured to cause (block S142) transmission, optionally based at least in part on the low PAPR precoder.

In accordance with one or more embodiments, the plurality of CRAM projection matrices are based at least in part on the signal subspace of the interfering wireless devices 22. In accordance with one or more embodiments, the signal subspace of a scheduled wireless device 22 corresponds to the eigenvectors associated with the channel response of the scheduled wireless device 22. In accordance with one or more embodiments, the signal subspace of the scheduled wireless device 22 is an M × K signal subspace, where M is the number of antennas of the network node 16, and K is the number of MIMO layers.

Having generally described an arrangement for using a signal subspace to at least partially generate and/or determine a projection matrix for wireless transmission, details of such arrangements, functions, and processes are provided below and may be implemented by the network node 16, the wireless device 22, and/or the host computer 24. Various examples and/or embodiments are described for determining, for example, CRAM projection matrices via processing circuitry 68. By substituting equation (2) for equation (1), the CRAM projection matrix can be rewritten as follows:

next, the channel matrix H_nCan be represented by its Singular Value Decomposition (SVD) component:

wherein:

·

containing the left singular vector;

·

is a diagonal matrix containing singular values;

·

containing the right singular vector.

Substituting (5) into (4) yields:

wherein

Eigenvectors that may correspond to the scheduled wireless device 22, an

Wherein:

·

is corresponding to

A diagonal matrix of eigenvalues of;

·

is a diagonal matrix lambda_nAnd is expressed as:

·

is an incomplete M × M identity matrix, with only the first K diagonal entries set to 1 and the remaining entries set to 0;

·

is WD22 signal at V_nThe columns in the matrix span and it corresponds to WD22 eigenvectors, also known as WD22 signal subspaces. As used herein, a signal subspace may refer to a subspace of scheduled wireless devices 22.

Equation (6) demonstrates how C can be directly represented by WD22 eigenvectors (i.e., the signal subspace of the scheduled wireless device 22)_nCRAM projection matrix. Thus, only the MxK signal subspace S_nIt may need to be communicated over the CRAM coefficient interface, which may require much less throughput than existing systems, as described herein. Because massive MIMO systems typically have more antennas than layers, M is often greater than K (M)>>K) And this approach results in a significant reduction in the throughput of the coefficient interface. In one or more embodiments, the signal subspace may be determined, via the processing circuitry 68, based at least in part on the assistance information provided by the one or more wireless devices 22. For example, in one or more embodiments, wireless device 22 may perform downlink channel estimation using channel estimation unit 34 and provide assistance information to network node 16 over radio interface 82 that indicates the signal subspace and/or channel response of wireless device 22 and/or some compressed information about the downlink channel properties described above.

The projection coefficients can be generated internally within CRAM unit 32 (i.e., CRAM processing engine, which is part of processing circuitry 68 using the last row of equation (6)) at a reasonable cost (i.e., a cost lower than that of existing systems). Due to the Hermite symmetry of the CRAM projection matrix, only calculations may be needed

An entry. Fig. 10 shows a block diagram of a first example of the present disclosure. In particular, like reference numerals in fig. 1 and 10 represent like functions, and thus these functions are not described in detail below. As shown in FIG. 10, CRAM processing has added projection matrix generation functions 94a-94n as described herein, such that CRAM cells 32 follow signal s₁-s_NAnd the signal subspace of the scheduled wireless device 22. As used herein, the bolded boxes in fig. 10-13 illustrate at least one of the functions added to generate the projection matrix inside CRAM cell 32.

This first example provides the following interface throughput reduction factor when compared to known systems:

in the above numerical example of a projection matrix, the CRAM coefficient interface throughput requirements using the signal subspace approach would be:

this is compared to 449.28Gbps described above. Seven SERDES channels (each at 16Gbps) may be employed to meet the above throughput requirements of the first example. Although CRAM unit 32 is shown as being within processor 70, CRAM unit 32 may be provided based on hardware and/or software and is not limited to implementation in only processor 70.

Interference aware transmission-second example

By using the signal subspace IF of the interference WD22 located in the neighbouring cell_nEnhancing signal subspace S of scheduled WD22_nReciprocity assisted interference aware transmission (RAIT) may be supported as follows:

in a second example, one or more of the subspaces IF of the interferer interfering with wireless device 22_nAlso transmitted over the interface, which results in an interface throughput reduction factor of:

wherein I_fIs the number of interference eigenvectors. Thus, in this example, the signal subspace S described herein is based at least in part on the CRAM cell 32 and/or the processing circuitry 68_nAnd IF_nAt least one CRAM projection matrix is determined, i.e.,

codebook-based transmission-example 3

In codebook-based transmission, the CRAM projection matrix is defined as:

wherein CB_nIs the matrix of the codebook used for subcarrier n.

Embodiment 3 causes a reduction in throughput requirements because, as shown in fig. 11, only the codebook index is passed through the interface, i.e., the codebook index is passed instead of the coefficient. Some copies of the codebook may be stored in one or more memories, such as memory 72, so that the projection matrix may be generated locally.

In particular, a total log may be employed per codebook index₂And (M) bit. The CRAM coefficient interface throughput requirements for this embodiment using codes would be:

this is in contrast to the 449.28Gbps throughput requirement described above, i.e., in one or more embodiments, the codebook indices are passed through the interface in CRAM unit 32 rather than the coefficients themselves.

In example 3, there are two contributions that contribute to reducing the interface throughput requirements, namely a reduction in the number of entries transmitted per PRB and a reduction in the number of bits per entry. For this embodiment, the throughput reduction factor is expressed as:

wherein Q_bitsIs the number of bits used to quantize both the real and imaginary parts of the CRAM projection coefficients.

Signal subspace acquisition from precoding solution-example 4

In example 4 shown in fig. 12, the CRAM coefficient interface is eliminated as shown in fig. 12. Signal subspaces are obtained from the precoded signals provided by precoder 2 using signal subspace tracking algorithms 96a-96b known in the art, which may be implemented in CRAM unit 32 and/or processing circuitry 68. In fig. 12, the box with the bold edge corresponds to the function added in place of the CRAM coefficient interface.

Acquisition of signal subspace from uplink channel-example 5

In example 5 shown in fig. 13, the signal subspace is acquired over the air, for example, by tracking the signal subspace in one or more uplink channels using one or more known tracking algorithms implemented by the CRAM unit 32 and/or the processing circuitry 68. The output of the signal subspace tracking function 96 in fig. 13 corresponds to the signal subspace S of the scheduled WD22_n. Tracking may be performed based on signals received via antennas 100-1 to 100-M of network node 16. The last row of equation (6) is then used by CRAM unit 32 and/or processing circuitry 68 to generate the CRAM projection matrix.

In addition, the signal subspace tracking function in fig. 13 may also track the signal subspace of the interference WD22 located in the neighboring cell to enable RAIT transmission. In such cases, the signal subspace tracking function also outputs a subspace IF of the interference WD22_nAnd a CRAM projection matrix is generated using equation (9). In other words, in this example, the signal subspace tracking function 96 tracks the signal subspace of the scheduled WD22 and/or the signal subspace of the interfering WD22, i.e., S_N|IF_N。

Thus, in one or more embodiments described herein, the CRAM projection matrix is processed as a function of signal subspace to reduce the CRAM coefficient interface throughput requirements. Using this approach, multiple beamforming schemes can be supported, such as reciprocity-based beamforming, RAIT, and codebook-based transmission. In one or more embodiments, the coefficient interface is eliminated by acquiring the precoded signal(s) provided from precoder 2 or acquiring the signal subspace of the scheduled WD 22-and optionally the subspace of the interferer-over the air by monitoring the uplink channel.

One or more of the processes described herein may be implemented in the cloud and/or by host computer 24. However, for the sake of latency, these RAN functions described herein may be implemented as close as possible to the antennas of the network node 16, i.e., may be collocated with the antennas of the network node 16.

Fig. 14 is a flow chart of an example process in the wireless device 22, in accordance with some embodiments of the present disclosure. One or more blocks and/or functions performed by wireless device 22 may be performed by one or more elements of wireless device 22, such as by channel estimation unit 34, processor 86, radio interface 82, etc. in processing circuitry 84. In one or more embodiments, the wireless device (such as via one or more of the processing circuitry 84, the processor 86, and the radio interface 82) is configured to provide (block S144) auxiliary information associated with a signal subspace of the wireless device 22, as described herein. In one or more embodiments, the wireless device 22 may estimate the wireless channel using known methods/processes, where the assistance information is based at least in part on the estimate. In one or more embodiments, the wireless device (such as via one or more of the processing circuitry 84, the processor 86, and the radio interface 82) is configured to receive (block S146) a transmission based at least in part on at least one CRAM projection matrix, wherein the at least one CRAM projection matrix is based at least in part on a signal subspace of a scheduled wireless device 22 that includes a signal subspace associated with the assistance information, as described herein.

In accordance with one or more embodiments, the at least one CRAM projection matrix is based at least in part on a signal subspace of the interfering wireless devices 22. In accordance with one or more embodiments, the at least one CRAM projection matrix is based, at least in part, on the at least one precoding codebook entry. In accordance with one or more embodiments, the signal subspace of a scheduled wireless device 22 corresponds to the eigenvectors associated with the channel response of the scheduled wireless device 22. In accordance with one or more embodiments, the signal subspace of the scheduled wireless device 22 is an M × K signal subspace, where M is the number of antennas of the network node 16, and K is the number of multiple-input multiple-output, MIMO, layers. According to one or more embodiments, the transmission is based at least in part on a multiple-input multiple-output, MIMO, precoder, wherein the MIMO precoder is based at least in part on at least one CRAM projection matrix.

As will be appreciated by one skilled in the art, the concepts described herein may be embodied as methods, data processing systems, computer program products, and/or computer storage media storing executable computer programs. Accordingly, the concepts described herein may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects that are all generally referred to herein as a "circuit" or "module". Any of the processes, steps, actions, and/or functionalities described herein may be performed by and/or associated with corresponding modules, which may be implemented in software and/or firmware and/or hardware. Furthermore, the present disclosure may take the form of a computer program product on a tangible computer-usable storage medium having computer program code embodied in the medium that is executable by a computer. Any suitable tangible computer readable medium may be utilized including hard disks, CD-ROMs, electronic memory devices, optical memory devices, or magnetic memory devices.

Some embodiments are described herein with reference to flowchart illustrations and/or block diagrams of methods, systems, and computer program products. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer (to thereby create a special purpose computer), special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory or storage medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function/act specified in the flowchart and/or block diagram block or blocks.

The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

It is to be understood that the functions/acts noted in the blocks may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Although some of the figures contain arrows on communication paths to illustrate the primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows.

Computer program code for performing the operations of the concepts described herein may be used such as

Or an object oriented programming language such as C + +. However, the computer program code for carrying out operations of the present disclosure may also be written in conventional procedural programming languages, such as the "C" programming language. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer. In the latter scenario, the remote computer may be connected to the user's computer through a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet service provider).

Many different embodiments have been disclosed herein in connection with the above description and the accompanying drawings. It will be understood that each combination and subcombination of the embodiments described and illustrated herein is overly duplicative and confusing. Accordingly, all embodiments can be combined in any manner and/or combination, and the description, including the figures, should be construed to constitute a complete written description of all combinations and subcombinations of the embodiments described herein, as well as the manner and process of making and using them, and shall support claims to any such combinations or subcombinations.

Abbreviations that may be used in the foregoing description include:

5G fifth generation cellular communication

CFR crest factor reduction

CP Cyclic Prefix

CRAM amplitude convex reduction

DPD digital predistortion

FFT fast Fourier transform

Inverse Fast Fourier Transform (IFFT)

LTE Long term evolution

MIMO multiple input multiple output

NR New air interface

OFDM

PA power amplifier

PAPR peak-to-average power ratio

PRB physical resource block

PS parallel to serial

RAIT reciprocity assisted interference aware transmission

SERDES serializer-deserializer

SP serial to parallel

SVD singular value decomposition

ZF zero forcing

It will be appreciated by persons skilled in the art that the embodiments described herein are not limited to what has been particularly shown and described hereinabove. Moreover, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. Many modifications and variations are possible in light of the above teaching without departing from the scope of the following claims.

Claims

1. A network node (16), the network node (16) comprising processing circuitry (68), the processing circuitry (68) configured to:

determining at least one amplitude Convex Reduction (CRAM) projection matrix based at least in part on a signal subspace of scheduled wireless devices (22); and

cause transmission based at least in part on the at least one CRAM projection matrix.

2. The network node (16) of claim 1, wherein the at least one CRAM projection matrix is based at least in part on a signal subspace of interfering wireless devices (22).

3. The network node (16) of claim 1, wherein the at least one CRAM projection matrix is based at least in part on at least one precoding codebook entry.

4. The network node (16) of claim 1, wherein the processing circuit (68) is further configured to: determining the signal subspace of the scheduled wireless device (22) based at least in part on tracking at least one uplink channel.

5. The network node (16) of claim 1, wherein the processing circuit (68) is further configured to: determining the signal subspace of the scheduled wireless device (22) based at least in part on tracking a precoded signal from a precoder (2).

6. The network node (16) of claim 1, wherein the processing circuit (68) is further configured to: receiving an indication of the signal subspace of the scheduled wireless device (22) from a precoded signal from a precoder (2).

7. The network node (16) of claim 1, wherein the processing circuit (68) is further configured to: receiving, from the scheduled wireless device (22), an indication of the signal subspace of the scheduled wireless device (22).

8. The network node (16) of claim 1 wherein the signal subspace of the scheduled wireless device (22) corresponds to an eigenvector associated with a channel response of the scheduled wireless device (22).

9. The network node (16) of claim 1, wherein the signal subspace of the scheduled wireless device (22) is an mxk signal subspace, where M is a number of antennas of the network node (16) and K is a number of multiple-input multiple-output, MIMO, layers.

10. The network node (16) of claim 1, wherein the processing circuit (68) is further configured to: determining a multiple-input multiple-output (MIMO) precoder based at least in part on the at least one CRAM projection matrix, the transmission being based at least in part on the MIMO precoder.

11. A method implemented in a network node (16), the method comprising:

determining (S134) at least one amplitude Convex Reduction (CRAM) projection matrix based at least in part on a signal subspace of scheduled wireless devices (22); and

causing (S136) a transmission based at least in part on the at least one CRAM projection matrix.

12. The method of claim 11, wherein the at least one CRAM projection matrix is based at least in part on a signal subspace of interfering wireless devices (22).

13. The method of claim 11, wherein the at least one CRAM projection matrix is based at least in part on at least one precoding codebook entry.

14. The method of claim 11, further comprising: determining the signal subspace of the scheduled wireless device (22) based at least in part on tracking at least one uplink channel.

15. The method of claim 11, further comprising: determining the signal subspace of the scheduled wireless device (22) based at least in part on tracking a precoded signal from a precoder (2).

16. The method of claim 11, further comprising: receiving an indication of the signal subspace of the scheduled wireless device (22) from a precoded signal from a precoder (2).

17. The method of claim 11, further comprising: receiving, from the scheduled wireless device (22), an indication of the signal subspace of the scheduled wireless device (22).

18. The method of claim 11, wherein the signal subspace of the scheduled wireless device (22) corresponds to an eigenvector associated with a channel response of the scheduled wireless device (22).

19. The method of claim 11, wherein the signal subspace of the scheduled wireless device (22) is an mxk signal subspace, where M is a number of antennas of the network node (16) and K is a number of multiple-input multiple-output, MIMO, layers.

20. The method of claim 11, further comprising: determining a multiple-input multiple-output (MIMO) precoder based at least in part on the at least one CRAM projection matrix, the transmission being based at least in part on the MIMO precoder.

21. A wireless device (22), the wireless device (22) comprising processing circuitry (84), the processing circuitry (84) configured to:

providing assistance information associated with a signal subspace of the wireless device (22); and

receiving a transmission based at least in part on at least one CRAM projection matrix, the at least one CRAM projection matrix being based at least in part on a signal subspace of scheduled wireless devices (22) that includes the signal subspace associated with the assistance information.

22. The wireless device (22) of claim 21 wherein the at least one CRAM projection matrix is based at least in part on a signal subspace of an interfering wireless device (22).

23. The wireless device (22) of claim 21, wherein the at least one CRAM projection matrix is based at least in part on at least one precoding codebook entry.

24. The wireless device (22) of claim 21 wherein the signal subspace of the scheduled wireless device (22) corresponds to an eigenvector associated with a channel response of the scheduled wireless device (22).

25. The wireless device (22) of claim 21 wherein the signal subspace of the scheduled wireless device (22) is an mxk signal subspace, where M is a number of antennas of a network node (16) and K is a number of multiple-input multiple-output, MIMO, layers.

26. The wireless device (22) of claim 21, wherein the transmission is based at least in part on a multiple-input multiple-output, MIMO, precoder that is based at least in part on the at least one CRAM projection matrix.

27. A method implemented in a wireless device (22), the method comprising:

providing (S144) assistance information associated with a signal subspace of the wireless device (22); and

receiving (S146) a transmission based at least in part on at least one CRAM projection matrix, the at least one CRAM projection matrix being based at least in part on a signal subspace of scheduled wireless devices (22) that includes the signal subspace associated with the assistance information.

28. The method of claim 27, wherein the at least one CRAM projection matrix is based at least in part on a signal subspace of interfering wireless devices (22).

29. The method of claim 27, wherein the at least one CRAM projection matrix is based at least in part on at least one precoding codebook entry.

30. The method of claim 27, wherein the signal subspace of the scheduled wireless device (22) corresponds to an eigenvector associated with a channel response of the scheduled wireless device (22).

31. The method of claim 27, wherein the signal subspace of the scheduled wireless device (22) is an mxk signal subspace, where M is a number of antennas of a network node (16) and K is a number of multiple-input multiple-output, MIMO, layers.

32. The method of claim 27, wherein the transmission is based at least in part on a multiple-input multiple-output (MIMO) precoder that is based at least in part on the at least one CRAM projection matrix.